LErTOGASTBINAE 



ROBBER FLIES OF THE WORLD 



313 



branch of the niedius. The rectangular, anterior cross- 

 vein enters the broad, discal cell at or barely beyond 

 the middle. The posterior crossvein is wanting 

 but the fourth posterior cell is short and the basal vein 

 on the posterior side of the discal cell is almost as long 

 as the distal vein on the posterior side of this cell. 

 Fourth posterior cell strongly narrowed at the margin, 

 anal cell closed with a short stalk. 



Abdomen : The abdomen is elongate and slender and 

 only slightly and gradually widened apically. There 

 is some coarse, long, pile on the middle of the sides 

 of the second tergite and some on the base of the 

 tergite except in the middle. The first tergite has 

 laterally a close-set linear row of 7 or 8 rather stout, 

 black bristles and some additional, more slender bristles. 



Distribution : Neotropical : Megonyx giganteus, new 

 species. 



Megonyx gigantens, new species 



Length 29 mm. Female. Head : The head is black 

 in ground color with a pale, whitish, clay brown, small 

 spot on the outside of the lower edge of the sub- 

 epistoma and the medial ridge of the subepistoma of 

 the same color. The black of the head is densely cov- 

 ered by pale, opaque grey pollen and micropubescence. 

 Palpus dark brown, a little lighter towards the base, 

 the lateral hairs whitish, the dorsal and the dorso- 

 lateral bristles or hairs black and 1 ventral black hair. 

 Pile and bristles of face black with 4 white hairs on 

 each side. Antenna black with only the extreme base 

 of the third segment minutely light brown. 



Thorax : The thorax is everywhere dull, opaque black, 

 except for the upper half of the proplenron, which is 

 light bluish grey or slate colored pollinose, relieved 

 by a small, black spot. Approximately the lateral 

 three-eighths of the mesonotum also opaque, pale, slate 

 grey pollinose, and this lateral pale stripe has a small, 

 medial, anteriorly rounded extension adjacent to the 

 humerus, and not reaching the anterior margin. Ante- 

 riorly the mesonotum is abruptly vertical, although 

 only moderately high. The humerus has dark, brown- 

 ish black pollen. Pleuron opaque black with a small, 

 horizontal, long, ovoid spot of pale grey pollen on the 

 upper part of the sternopleuron. Anteriorly and 

 posteriorly to this grey spot there is a diffuse spot of 

 brown poilen. Metapleuron with a horizontal row of 

 some 15 rather short, slender, black bristles or long, 

 black setae, placed irregularly. Scutellum pale slate 

 grey pollinose. All thoracic pile and bristles black. 



Legs : The hind femur is shining black on the outer 

 three- fourths, including the apex ; the basal part dark, 

 reddish brown. Hind tibia with the basal two-fifths 

 black and the apical tenth black, the intermediate por- 

 tion quite pale brownish yellow or clay colored and 

 with mostly pile of the same color. The black portion 

 of the tibia and the whole of the femur with black 

 pile. Middle femur black, becoming reddish only ven- 

 trally and basally. Its dense, appressed setae are black 

 and with a few basal, posterior, whitish hairs. Middle 



tibia brownish black with an obscure, linear, dorsal 

 and basal, yellowish white streak and a larger, simi- 

 larly colored stripe on the outer two-fifths but con- 

 fined to the dorsal half of the posterior surface and 

 not reaching the apex. The setae almost entirely black 

 but with some intermixed white elements posteriorly. 

 Hind tarsi black, the apical segment with a yellowish 

 brown spot in the middle dorsally. Middle tarsi black 

 with the basal segment extensively yellowish wliite pos- 

 teriorly nearly to the apex and less extensively pale 

 anteriorly. Claws wholly black and tarsal pile almost 

 wholly black. 



Wings : The wings are strongly tinged with brownish 

 black with purple reflections but obscurely and slightly 

 paler along the posterior margins. All veins quite 

 black. There is an elongate, small but conspicuous, 

 subrhomboid spot which is hyaline in the second basal 

 cell and situated just before the origin of the discal 

 cell, and a second smaller, similar hyaline spot obtusely 

 triangular below the base of the discal cell in the second 

 basal cell. Basal fork of the fourth vein with a small, 

 pale spot. 



Abdomen : The abdomen is black, the basal two-fifths 

 of the second tergite is pale grey pollinose and the 

 posterolateral portion of this tergite is also pale grey 

 pollinose. The third, fourth and fifth tergites similar, 

 the basal band of pollen less extensive and the posterior 

 spots also becoming smaller. Pile of abdomen mod- 

 erately abundant, appressed and black and setate. 



Type: Female, Manaus, Amazonas, Brazil, October 

 1945, collected by W. Praetorius. Donated to the 

 American Museum of Natural History by Frank 

 Johnson. 



Genus Schildia Aldrich 



FiouEES 201, 588, 1192, 1201 



Schildia Aldrich, Proc. U.S. Nat. Mus., vol. 62, p. 4, 1923. 

 Type of genus: Schildia tnicrothorax Aldrich, 1923, by 

 original designation. 



Schildia has 1 subgenus, Shannomyioleptus Carrera. 



Small flies of remarkably slender, elongate abdomen, 

 elongate and slender hind legs and with the wings 

 characterized by the presence of long, stout setae on the 

 last branch of the radius and the first two branches 

 of the medius. The veins of the radial sector at the 

 apex tend to be compressed together ending within a 

 short distance of one another near the apex. Shan- 

 nomyioleptus Carrera is a subgenus of Schildia, 

 differing in the slightly longer antenna and the slightly 

 more extensive distribution of the neural setae. 

 Length 6 mm. 



Head, lateral aspect : The head is long, strongly con- 

 vex both on the anterior and posterior half, the face 

 plane with the eye, the occiput rather prominent behind. 

 The proboscis is short, cylindrical, extended forward, 

 the apex bluntly rounded. Palpus of one segment, 

 extremely minute and short. The antenna is attached 

 at the upper fifth or sixth of the head and rather short, 



